Composite signalling device



Feb. M, 1967 w. R. AIKEN COMPOSITE SIGNALLING DEVICE 4 Sheets-Sheet 1 Filed June 1, 1964 INVENTOR. WILLIAM ROSS AIKEN Feb. 14, 1967 w. R. AIKEN 3,

COMPOSITE SIGNALLING DEVICE Filed June 1, 1964 V 4 Sheets-Sheet 5 United States Patent Office 3,364,549 CUMFGflITE SIGNALLING DEVICE William R. Aiken, Los Altos Hills, Caiifi, assignor to Electronin Ten, Inc, San Francisco, Calif., a corporation of (Ialifornia Filed June 1, H64, Ser. No. 371,637 11 Claims. (Cl. 340373) The present invention relates to adjustable signal-ling devices of the type employing relatively movable compo nents to display, expose and/or conceal an identifying mar-k, such as a warning inscription, a number, a colored area and the like. More particularly the present invention relates to signalling devices of the type referred to wherein the relative movement of the mark displaying and concealing components is accomplished by the repelling and/ or attracting effect of electrostatic charges. Such signalling devices are described in my U.S. Patents 2,912,674, 2,952,835 and 3,089,120. In devices of this type a sheet or vane may be hingedly connected to a base of conductive material for movement from a position adjacent to said base to a position folded away from said base and the movement of said vane is effected by applying an electric charge jointly to said vane and said base to repel the vane from the base in the same manner in which the leaves of an electroscope repel each other, and/or by applying an opposite charge to suitably placed electrode members which attract the vane into a position folded away from the base.

Devices of the type described may be assembled into groups of vertically superposed horizontal rows of juxtaposed units, or expressed differently, groups of juxtaposed vertical rows of superposed units, and adjustment of selected ones of the assembled units to positions wherein the outer surfaces of their vanes are exposed to view, may be employed to form large and clearly visible letters, numbers and like symbols as disclosed in my aforementioned Patent No. 3,089,120.

It is an object of the present invention to provide a simple and effective switch arrangement for selectively controlling the position of the individual units of a composite signalling apparatus of the type referred to.

More specifically, it is an object of my invention to provide an arrangement, of the type referred to, by means of which any single one or any selected group of the individual units of a composite signalling apparatus may selectively be activated, without requiring individual switches for all the units comprised in the composite signalling device.

Still another object of the invention is to provide a composite signalling apparatus of the type referred to, that may be operated to display any desired letter or symbol, with a limited number of switches, and in fact with a number of switches that is only a fraction of the number of units comprised in the apparatus.

An additional object of the present invention is to provide mechanisms for automatically actuating the proper control switches of a composite display apparatus, to display a desired symbol or sequence of symbols.

These and other objects of the present invention will be apparent from the following description of the accompanying drawings which illustrate certain preferred embodiments thereof and wherein FIGURE 1 is a perspective, partly in section, of one of the signalling units of the composite display apparatus of the invention;

FIGURES 2A, 2B and 2C are schematic vertical sections through the device shown in FIGURE 1 illustrating different operational positions thereof;

FIGURE 3 is a schematic front elevation of a composite display apparatus embodying the invention, and

33%,549 Patented Feb. 14, I967 shows the complete control circuitry for the individual signalling units thereof;

FIGURE 4 is a schematic perspective of a mechanism for selectively operating the switch arrangement illustrated in FIGURE 3;

FIGURE 5 is a fragmentary plan view of a punched tape employed on the mechanism of FIGURE 4 to selectively actuate the switch arrangement shown in FIGURE 3;

FIGURE 6 is a schematic front elevation of the composite display apparatus of the invention as activated by the punched tape shown in FIGURE 5;

FIGURE 7 is a schematic perspective similar to FIG- URE 4, of another mechanism for automatically setting the switch arrangement shown in FIGURE 3 to cause display of a desired symbol.

The individual units U of the composite display apparatus of my invention comprise a base It which may be of a suitable plastic material. Upon said base is supported an electrode in the form of a thin sheet 12 of electrically conductive material such as metal foil glued to said base or a coat of conductive paint. Another thin sheet or vane 14 which may likewise be made from metal foil, but may also be made from poorly conductive materials, such as the plastic known under the name of Cellophane, is hingedly supported from the base 10 near the front edge thereof in any suitable manner such as by means of flexible hinge strips 16, for swinging movement from a substantially horizontal position adjacent to but spaced from the base 10 (FIGURE 2A) into a substantially vertical position (FIGURE 2C). The upper surface of the vane 14 may be provided with a coat of vividly colored paint, such as red or yellow, as indicated with exaggerated thickness at 18 in FIGURES 2A, 2B and 2C.

The unit U may also have a pair of vertical side walls 20:: and 20b whose inner surfaces carry electrodes 21:: and 21b, respectively. It may also have a horizontally disposed roof or ceiling 22 whose inner surf-ace is provided with an electrode 24. The side walls 20a and 20b and the roof 22 may be made of the same plastic material as, and may in fact form an integral structure with, the base It). The front of each unit may be left open or may be closed by a window pane 26 of a suitable material, such as glass or a transparent plastic.

In the particular embodiment of the invention illustrated in the accompanying drawings, the base electrode 12 and the vane 14 are conductively connected with each other and both are grounded by a common lead 28 as schematically indicated in FIGURES 2A, 2B and 2C. The side electrodes 21a. and 21b are conductively connected as indicated schematically by the lead 30, and may jointly be connected to a source of positive potential by means of an initially open switch 32. The top electrode 24 may be connected to the same source of positive potential by means of a separate initially open switch 34. As long as the switches 32 and 34 are open, the vane 14 remains in a position substantially parallel and adjacent to the base electrode 12 but is slightly spaced from said base electrode by suitable spacer beads indicated at 36, which may be made of metal or insulating material. In this position the outer surface 18 is not visible through window 26.

In accordance with the invention the vane is raised to a position wherein its outer surface is exposed to the outside through the window 26 (FIGURE 2C) by closing two separate switches 32 and 34 to apply attracting poten tials to the electrodes 21a, 21b and 24- rather than by a single switch that is common to said electrodes. When switch 32 alone is closed, the application of positive potentials to the side electrodes 21a and 21b is effective to raise the vane to an inclined position such as illustrated in FIGURE 23 but is insufficient to raise the vane fully,

since beyond a certain angular position of said vane the portions of the side electrodes above and below the vane exert equal amounts of oppositely directed electrostatic attraction upon said vane. As a rule, therefore, when attracting potentials are applied to the side electrodes, the vane will rise to, and remain in, an inclined position of no more than 45 wherein its outer surface 18 is scarcely visible from the outside (FIGURE 2B). Upon closure of both, switch 32 and switch 34, however, the attracting potential applied to the top electrode 24 exerts an additional attraction upon the partially raised vane and lifts it to an almost vertical position as illustrated in FIGURE 2C, wherein it exposes its outer surface 18 fully to the outside through the window 26.

In embodiments of the invention which have a window pane 26, it is possible to achieve a truly vertical position for the vane by applying an attracting potential :to the window pane 26. For this purpose the inner surface of the pane may be covered with a coat of a transparent conductive material indicated at 38 in FIGURES 2A, 2B and 2C and a switch 42 may be provided that may be set to connect said conductive coat to the source of positive potential. A similar effect may be obtained by providing a circumferential frame of Silver paint 44 (FIGURE 1) upon the inner surface of the window pane adjacent the edges thereof and connecting said frame to a source of positive potential. In the event that the above described means are provided on the window pane for raising the vane 14 fully into vertical position, it is advisable to provide spacer elements upon the inner surface of the pane such as shown at 46 to prevent conductive contact of the vane with the window.

The described method of raising the vane with the aid of two separate switches into its fully effective position, makes it possible to activate the individual signalling units of a composite multi-unit display apparatus with only a fraction of the number of switches that would ordinarily be required to permit individual activation of every one of the units comprised in the apparatus. FIG- URE 3 shows a somewhat schematic representation of a composite signalling apparatus of the type to which the present invention applies. It comprises six vertically superposed horizontal rows H of nine horizontally juxtaposed units U or to put it differently, nine juxtaposed vertical rows V of each six superposed units, and by activating selected ones of said units so that they expose the outer surfaces of their vanes through their front windows, any desired symbol may be formed upon the front face of the apparatus, such as the number 4 shown in FIG- URE 6.

Each of the units comprised in the embodiment of the invention illustrated in FIGURES 3 and 6 comprises a base electrode 12 and a hingedly supported vane 14 which are in electrically conductive contact with each other; and the base electrodes and vanes of all the units in each of the nine vertical columns V are connected to common vertical leads 48 that rise from a common horizontal lead 47 which is grounded as indicated at 49. In the embodiment of the invention illustrated in FIGURE 3, the adjacently positioned units in each horizontal row H have common side electrodes 21 and all the side electrodes in each horizontal row H are conductively connected to a common horizontal lead 50; and every one of the six horizontal leads t) comprised in the apparatus may be individually connected to a source of positive potential 51 by individual, normally open switches S S S S S and S respectively. Each of the units in the display apparatus illustrated in FIGURE 3 also has a top or ceiling electrode 24, and all the top electrodes 24 in each of the nine vertical columns V in the apparatus are conductively connected to a vertical lead 52; and every one of the nine vertical leads 52 comprised in the apparatus may individually be connected to the source of positive potential 51 by a normally open individual switch T T T T T T T T and T respectively.

In accordance with the invention every one of the fiftyfour units comprised in the display apparatus may selectively be activated by appropriate joint manipulation of one of the six switches S to S and one of the nine switches T to T Let it be assumed, for instance, that it is desired to activate the third unit (counting from the top) in the fourth vertical column (counting from the left). All that is necessary for the operator is that he close switches S and T Closure of switch S raises the vanes of all the units in the third horizontal row H to a slightly incline-d position but does not by itself effectively expose the outer surface 18 of any one of the vanes in said units to view through the window 26. Closure of switch T by itself is ineffective to raise the vanes of the units in the fourth vertical column V to any appreciable extent. In case of the fourth unit in the third horizontal row H however, closure of switches S and T is effective to energize the side electrodes as well as the top electrode, and the vane 14 of said unit therefore swings into a practically vertical position wherein its outer surface 18 is fully exposed to view (FIGURE 3).

If the units of the composite display apparatus illustrated in FIGURE 3, are provided with transparent front windows 26 which are made of conductive material or are provided with transparent conductive coatings or circumferential frames of conductive metal paint as explained hereinbefore, said windows or their conductive components may be connected to common horizontal leads 54 that are jointly connected to the source of positive potential by the switch 42. When said switch is closed, any vane 14 that may have been raised into effective position by closure of the appropriate switches S and T will assume a fully vertical position wherein its signalling surface 18 is clearly visible from the outside and will remain in this position even after the switches S and T that raised it into its effective position are reopened. Thus, the control vane of any one of the signalling units comprised in the display apparatus of the invention may be placed into effective position by closure of the appropriate switches S and T, and will remain in effective position after said switches have been reopened, provided switch 42 remains in a position wherein it connects the window to a source of an attracting potential. This means that neither of the switches S and T that were required for swinging the vane of a selected unit into its fully elevated position, are required for maintaining the unit in its activated position. Therefore, upon activation of a selected unit, all the switches S and T comprised in the apparatus of the invention may be opened and are again available for activating other selected units. It will be understood that the same results may be obtained by connecting all the windows (or their conductive components) in the vertical rows V of signallmg units to common conductive leads 55 that are jointly connected to a source of an attracting potential through the switch 42.

After a symbol has been set up on the face of the apparatus and has served its purpose, it may be cleared from the display surface by setting the switch 42 to a position wherein they connect the window panes of all the units to a neutral or repelling potential. In the hereinbefore described exemplary embodiment of the inventron wherein positive potentials are employed to attract the swinging sheets into their effective positions, the switch 42 may therefore be set to connect the window panes in the horizontal or vertical rows H and V, respectively, to a source of negative potential as indicated in FIGURE 3. It may be suflicient, however, to connect the window panes to ground. To effect proper return of the vanes 14 to their initial positions, they may be provided with suitable return springs indicated at 57 in FIG- URES 2A, 2B and 20. Alternatively, the spacers 46 on the window panes 26 may be made sufficiently long to prevent the vanes from ever reaching a precisely vertical position so that they may drop back into their initial 5 positions under the force of gravity when the attracting potential is removed from the window pane. To accelerate the desired return movement of the vanes, counterweights 58 may be attached to the rear surfaces of the vanespreferably at points that are relatively close to the axes of rotation of said vanes.

The described arrangement for individually activating selected ones of the display units to set up a desired symbol upon the display surface of the apparatus lends itself exceptionally well to automatic control operation. Thus, the switches T and S can be arranged in such a manner that they may be actuated by perforated program tapes to set up desired symbols and clear the symbols out after a predetermined period of display. Having referenceto FIGURE 4, the switches S are formed by an electrically conductive bar 60 that is countersunk in and extends transversely across an elongated table plate 62 of electrically non-conductive material, and by six transversely spaced contact members 64 that are arranged above the bar 60 and which have at their bottom ends jresilient contact lips 66 that are normally urged into conductive contact with said bar 60. Each of said contact members 64 is connected to one of the horizontal leads '50 of the display apparatus, and said bar 60 is electrically connected to the source of positive potential 51 as schematically indicated. The switches T to T are formed by a longitudinally extending bar 68 of electrically conductive material that is countersunk in the table plate 62 along a longitudinal edge thereof, and by nine contact members 70 that are arranged above said bar 68 and which are provided with resilient lips 72 that are urged into contact with the bar 68. Initially, the contact lips of all the contact members 64 and 70 are electrically insulated from the bars 60 and 68, respectively, by a tape 74 of paper or the like. Said tape is wound upon a supply reel 75 arranged at one of the end edges of the table 62, and is drawn over and along said table between the lips of said contact members 64 and 70 and the conductive bars 60 and 68, respectively, by operation of a combined drive and take-up reel 76 that is arranged adjacent the opposite end edge of said table 62. In predetermined areas the tape 74 contains perforations '78 that permit selected ones of the contact members 64 and '70 to make contact with the conductive bars 60 or 68, as the case may be, for brief periods of time as the tape is pulled across the table by clockwise rotation of the take-up reel 76.

.Let it be assumed that it is desired to set up the number 4 on the display surface of the apparatus in the manner shown in FIGURE 6. For this purpose the part of tape 74 (FIGURE 5) that is to set up the number 4 on the display apparatus has a single perforation P that travels over and along the longitudinal contact bar 63 as the tape is pulled over the table. In this manner every one of the contact members 70 of the switches T to T is perimitted in quick succession to make contact with said bar ,68 so that positive potentials are briefly applied to the top electrodes 24 in all units of the nine vertical columns V. As the perforation P passes underneath the contact members of switches T and T this remains without noticeable effect upon the display surface of the apparatus because during this time none of the contact members of the switches S to S is allowed to make contact with their contact bar 60. Thevanes 14 in the first two columns of superposed signalling units V and V are therefore unable to rise significantly and their outer surfaces remain invisible from the outside; and they retain their initial subslide underneath the contact members of switches S S S and S and permit said members to make conductive contact with the cross bar 60. Thus, while all the top electrodes 24 in the third column V of vertically superposed units U are energized, all the side electrodes 21 in the first four horizontal rows H H H and H; of juxta posed units are also energized. Hence, in the four upper units of the third vertical column V the side electrodes as well as the top electrodes are energized. This is effective to raise the vanes 14 in said units to practically vertical position so that they clearly expose their outer surfaces 18 to the outside. In the remaining units of the four uppermost horizontal rows H H H and H energization of the side electrodes 21 merely operates to raise the vanes 14 into an inclined position (FIGURE 2B), and as the tape 74 moves on and withdraws the four transversely aligned holes P P P and P from underneath the contact members of switches S S S and S these partially raised vanes drop back into their substantially horizontal inactive positions. The four fully raised vanes in the upper four units of the third vertical column V however, remain in their display positions because they have come into the effective range of the positive electrostatic field set up by the charge upon the window panes 26 in said units. As the tape moves on and places the lateral perforation P underneath the contact member for the top electrodes of the fourth column V of superposed units, the four transversely aligned perforations P P P and P are withdrawn from underneath the contact members 64 of switches S S S and S and a single perforation P which is aligned with the contact member of switch 8., moves underneath said contact member. As a result thereof both the top electrode and the side electrodes of the fourth unit (counted from the top) in the fourth vertical column V are energized, and the vane 14 in said unit assumes its proper display position, and remains in display position even after continued advance of the tape withdraws the laterally located perforation P from the contact member of switch T and the perforation P from underneath the contact member of switch S As continued advance of the tape moves the perforation P underneath the contact member of switch T a row of six transversely aligned perforations P P P P P and P moves underneath the contact members of switches S to S and as a result thereof the vanes of all the units of the fifth vertical column V swing into vertical position and remain in this position after the continued advance of the tape is effective to reopen switch T and all of switches S to S Then, as the perforation P moves underneath the contact'member of switch T and closes said switch temporarily, another perforation P moves underneath the contact member of switch S and closes said switch S temporarily causing full activation of the fourth unit (counted from the top) in the sixth vertical column V and finally as the perforation P becomes effective to briefly close switch T another perforation P in the tape 74 operates to briefly close switch 8,; again so that the fourth unit in the seventh vertical row is also fully activated. The composite signalling apparatus of the invention now displays clearly the numeral 4 upon its face (FIGURE 6) and will continue to do so until switch 42 is set to connect the conductive areas of the window panes 26 of all the units in the apparatus of the invention to a repelling potential voltage. The charge thus placed upon the window panes is effective to repel all the activated vanes 14 so that they drop into their horizontal positions wherein their signal forming surfaces are no longer discernable from the outside. The displayed symbol has thus been cleared from the apparatus and upon return of switch 42 to its initial position wherein it applies a positive potential to the conductive areas of the window panes, the apparatus is in con dition to display another sign or symbol.

The arrangement for controlling the operation of the display apparatus of the invention, which is illustrated in FIGURE 7, is similar in construction and performance to the arrangement illustrated in FIGURES 4 and 5. It dili'ers from the arrangement illustrated in FIGURE 4 in that it employs, in place of the mechanical switching members 60/64 and 68/72, photosensitive elements whose conductivity is controlled by light that may reach, and modify the resistance value of, said elements through the perforations of the moving tape.

Having reference to FIGURE 7 the switches S to S are formed by six relatively spaced blocks 80 of photosensitive material, that are countersunk in an elongated table plate 82 of insulating material in a direction transversely across said table. The material from which the blocks 80 are made is such that it is practically non-conductive as long as it remains in darkness but becomes conductive when exposed to light. Similarly, the switches T to T are formed by nine blocks 84 of a photosensitive material that are countersunk in said table plate along a longitudinal edge thereof. Arranged above the blocks 80 is an elongated source of light 86, and arranged above the blocks 84 is another elongated source of light 88. A program tape 90 wound upon a supply reel 92 and drawn across the table plate 82 by a combined drive and takeup reel 94, protects the blocks of photosensitive materials 30 and 84 initially from the light emitted by the lamps 86 and 88, respectively. The tape 90, however, contains appropriately placed perforations P in line with the blocks 80 and 84 in the same manner as the program tape illustrated in FIGURES 4 and and when these perforations move over the blocks 80 and/or 84, as the case may be, during operation of the drive reel 94, light from the lamps 86 and 88 may briefly impinge upon said blocks and render them temporarily conductive. Thus, advance of an appropriately perforated program tape may be made to control the activation of selected individual units of a composite display apparatus constructed in accordance with the invention and cause it to display desired symbols in the same manner as described in connection with the automatic control mechanism represented by FIGURES 4 and 5.

It remains to point out that the signalling units of the invention may be operated by repelling and attracting potentials other than those specifically mentioned and illustrated in connection with FIGURES 2A, 2B and 2C. Thus, the base electrode 12, the vane 14, the side electrodes 21 and the top electrode 24 may all initially be connected to a source of positive potential while the window pane 26 may be connected to ground; and elevation of the vane 14 into vertical, or nearly vertical, position may be achieved by connecting the side electrodes and the top electrode independently to ground while retaining positive potentials on the base electrode and the vane. Return of an activated vane 14 to its inactive, substantially horizontal position may then be accomplished by applying first a repelling positive potential to the Window pane 26 by manipulation of switch 42. This drives the vane backwards out of its dead center position. Thereafter the switches 32 and 34 are manipulated to re-establish repelling positive potentials on the top and the side electrodes. It will be understood that in order to speed up operation of the device of the invention, it may be of advantage to provide special means, such as leak resistors and/or suitable, switch-controlled connections for dissipating the electrostatic charges placed upon the electrodes 21a, 21b, 24 and 38 by closure of switches 32, 34 and 42, respectively, when said switches are opened.

While I have explained my invention with the aid of a particular embodiment thereof, it will be understood that the invention is not limited to the specific constructional details shown and described by way of example, which may be departed from without departing from the scope and spirit of my invention.

I claim:

1. A display apparatus employing physically movable components comprising an array of individual signalling units arranged to form a set of superposed horizontal rows of juxtaposed units and a set of juxtaposed vertical rows of superposed units, each unit having a vane mounted for movement from a concealed position to an exposed position, and means for moving the vanes of each of said units individually from said concealed to said exposed position including first and second electrodes located adjacent the path of movement of said vanes in each of said units; individual means for each of the rows in one of said sets for applying a vane-moving potential to the first electrodes of all the units comprised in the row and individual means for each of the rows in the other one of said sets for applying a vane-moving potential to the second electrodes of all the units comprised in the row.

2. A display apparatus comprising an array of individual signalling units arranged to form a set of superposed horizontal rows of juxtaposed units and a set of juxtaposed vertical rows of superposed units, each unit having a vane mounted for movement from a position wherein it is concealed from view to a position wherein it is exposed to view, and means for moving the vanes in every one of said units individually from said concealed to said exposed position including a side electrode and a top electrode in each of said units, individual means for each of the rows in one of said sets for applying a vane-moving potential to the side electrodes of all the units comprised in the row and individual means for each of the rows in the other one of said sets for applying a vane-moving potential to the top electrodes of all the units comprised in the row.

3. A display apparatus comprising an array of individual signalling units arranged to form a set of superposed horizontal rows of juxtaposed units and a set of juxtaposed vertical rows of superposed units, each unit having a vertically disposed window and a vane mounted for movement from a substantially horizontal position wherein it is conceaied from view through said window to a substantially vertical position adjacent said window wherein it is exposed to view through said window, and means for moving the vanes of each of the units individually from said concealed to said exposed position including in each of said units laterally placed electrodes and a top electrode located above said vane, individual means including a switch for each of the rows in one of said sets for applying a vane-moving potential to the side electrodes of all the units comprised in the row, and individual means including a switch for each of the rows in the other one of said sets for applying a vane-moving potential to the top electrodes of all the units comprised in the row.

4. A display apparatus comprising an array of individual signalling units arranged to form a set of superposed horizontal rows of juxtaposed units and a set of juxtaposed vertical rows of superposed units, each unit having a window and a vane mounted for movement from a position wherein it is concealed from view through said window to a position wherein it is exposed to view through said window, and means for moving the vanes in everyone of said units individually from said concealed to said exposed position including aside electrode and a top electrode in each of said units, individual means for each of the rows in one of said sets for applying a vane-moving potential to the side electrodes of all the units comprised in the row, individual means for each of the rows in the other one of said sets for applying a vane-moving potential to the top electrodes of all the units comprised in the row, and means for applying a vane-repelling potential to the windows of all the units comprised in the apparatus.

5. A display apparatus comprising an array of individual signalling units arranged to form a set of superposed horizontal rows of juxtaposed units and a set of juxtaposed vertical rows of superposed units, each unit including a vertically disposed window having a conductive area, a vane mounted for movement between a substantially horizontal position wherein it is concealed from view through said window and a substantially vertical position wherein it is exposed to view through said window, and means for moving the vanes of every one of the units individually from said concealed to said exposed position including in each of the units side electrodes placed laterally of said vane and a top electrode located above said vane, individual means including a switch for each of the rows in one of said sets for applying a vane-moving potential to the side electrodes of all the units comprised in the row, individual means including a switch for each of the rows in the other one of said sets for applying a vanemoving potential to the top electrodes of all the units comprised'in a row; and means for selectively applying vaneattracting and vane-repelling potentials to the windows of all the units comprised in the apparatus.

6. A signalling device comprising a base of insulating material, a vane hingedly supported for swinging movement from a first position wherein it is concealed from view to a second position at right angles to said first position wherein it is exposed to view; means for moving said vane from said first to said second position including a first electrode arranged adjacent said vane in said second position thereof, second electrodes arranged at either side of said vane, and means including separate switches for applying vane-attracting potentials separately to said first and second electrodes.

7. A signalling device comprising a horizontally disposed base of insulating material, a sheet-shaped electrode upon said base, a vane hingedly supported for swinging movement from a first position adjacent said base wherein it is concealed from view to a second position wherein it is exposed to view; and means for moving said vane from said first to said second position including vertically disposed sheet-shaped electrodes arranged at either side of said vane, a top electrode arranged above said vane, and means having separate switches for applying vaneattracting potentials separately to said side electrodes and said top electrode.

8. A signalling device comprising a horizontally disposed base of insulating material, a sheet-shaped electrode upon said base, a window having a conductive area disposed vertically adjacent said base, a vane hingedly supported for swinging movement from a first position adjacent said base wherein it is concealed from view through said window to a second position adjacent said window wherein it is exposed to view through said window, means for moving said vane from said first to said second position including vertically disposed electrodes arranged at either side of said vane, a horizontally disposed top electrode arranged above said vane, and means including separate switches for applying vane-attracting potentials separately to said side electrodes and said top electrode; and means operable to selectively apply vaneattracting and vane-repelling potentials to said window.

9. A device according to claim 8 including a restore spring for said vane.

10. A signalling device comprising a horizontally disposed base of insulating material, a sheet-shaped electrode upon said base, a window having a conductive area disposed vertically adjacent said base, a vane hingedly supported for folding movement from a first position adjacent said base wherein it is concealed from view through said window to a second position adjacent said window wherein it is exposed to view through said Window; spacer means upon said base for maintaining said vane in said first position thereof at a slight inclination relative to the plane of said base; means for moving said vane from said first to said second position including vertically disposed electrodes arranged at either side of said vane, a horizontally disposed top electrode arranged above said vane, and means including separate switches for applying vane-attracting potentials separately to said side electrodes and said top electrode; spacer means on said window for maintaining said vane in said second position thereof in a slightly reclined condition; and means operable to selectively apply vane-attracting and vane-repelling potentials to said window.

11. A device according to claim 10 including a counterweight attached to the rear surface of said vane near the hinge support thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,773,645 12/1956 Speh 235-6l.11 2,831,634 4/1958 Juhn 235-61.11 2,952,835 9/1960 Aiken 340-44 3,042,823 7/1962 Willard 3136 3,089,120 5/1963 Aiken 340-44 NEIL C. READ, Primary Examiner. I, J. LEVIN, Assistant Examiner. 

1. A DISPLAY APPARATUS EMPLOYING PHYSICALLY MOVABLE COMPONENTS COMPRISING AN ARRAY OF INDIVIDUAL SIGNALLING UNITS ARRANGED TO FORM A SET OF SUPERPOSED HORIZONTAL ROWS OF JUXTAPOSED UNITS AND A SET OF JUXTAPOSED VERTICAL ROWS OF SUPERPOSED UNITS, EACH UNIT HAVING A VANE MOUNTED FOR MOVEMENT FROM A CONCEALED POSITION TO AN EXPOSED POSITION, AND MEANS FOR MOVING THE VANES OF EACH OF SAID UNITS INDIVIDUALLY FROM SAID CONCEALED TO SAID EXPOSED POSITION INCLUDING FIRST AND SECOND ELECTRODES LOCATED ADJACENT THE PATH OF MOVEMENT OF SAID VANES IN EACH OF SAID UNITS; INDIVIDUAL MEANS FOR EACH OF THE ROWS IN ONE OF SAID SETS FOR 